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Evolution Of Man's Best Friend

Man's best friends come in many shapes, sizes, colors and textures because of thousands of years of evolution and breeding.

In February, researchers attempting to explain these differences presented the latest theory's at the national meeting of the American Association for the Advancement of Science.The Saturday Early Show resident veterinarian Debbye Turner provided some details on the latest Pet Planet.

Based on genetic research, one study theorized that all dogs were bred from a pack of wolves in East Asia at least 100,000 years ago. Another categorizes all 300 dog breeds from around the world that exist today into ten distinct, and separate groups.

Turner says it's important to note that these are theories, not scientific facts, and are considered controversial to some people.

Here in the U.S., the American Kennel Club recognizes 150 different dog breeds that are separated into seven groups (sporting, hound, working, terrier, toy, non-sporting, herding, and miscellaneous).

Turner says all dogs can interbreed and they all have 39 pairs of chromosomes that are essentially identical. But how is it possible for a Maltese to come from the same ancestor as a Old English Sheepdog?

Researchers, Deborah A. Lynch and Jenny Madeoy gathered information from a wide variety of sources (including ancient artifacts, tapestries, paintings, notes and oral histories) and theorize that all dogs fall into one of ten "progenitor breeds."

Progenitor breeds are breeds that have unique and heritable characteristics that likely contribute to the development of other breeds. The progenitor breeds include Sight Hounds, Scent Hounds, Working and Guard Dogs, Toy and Companion Dogs, Northern Breeds, Flushing Spaniels, Water Spaniels and Retrievers, Pointers, Terriers and Herding.

Sight Hounds:Greyhounds were depicted hunting gazelle in artwork from 5,000 B.C. With its sleek body, long limb and fast speed, the greyhound is built to hunt.

This group is called sight hounds because they hunt by using their sight (as opposed to smell). "Sight Hounds" have an extraordinary ability to discern movement from great distances. Their deep chests and long, wiry limbs allow for the speeds necessary to catch their prey.

Scent Hounds:Dogs in this group hunt by smell. The dog's nose is believed to be 100,000 times more sensitive than a human's. These dogs have been known to follow a scent for more than 50 miles. Many of these dogs have lots of "extra" skin on the head. This loose skin and soft ears help them stir up and trap scent. In the 12th century, monasteries kept packs of hound. The monks took such great care of these hounds that they became known as "blooded hounds" meaning aristocratic.

This group includes: Bloodhound, Black and Tan Hound, Dachshund, Otterhound, Bassett Hound, English Foxhound, American Foxhound

Working and Guard Dogs:The gentle giant, the Mastiff, belongs to this group. It's the Mastiff was were trained for combat and guarding temples. The dog was also used for hunting and as in war. The broad head provided for a wide mouth, making the jaws power weapons in combat. But, the modern Mastiff has been bred to have a mild temperament, making them good companions and family pets.

Toy and Companion Dogs:The Maltese is considered one of the earliest progenitors of the toy group. The breed is commonly believed to get its name from the island of Malta. It's also believed that Maltese dogs have always been kept as companions to humans which would explain their petite size and mild manner.

Flushing Spaniel:Many of these dogs have long, feathered hair on the chest and legs. This "feathering" helps protect the dog from brush, burrs, and thorns while hunting. They usually are low to the ground to facilitate running under and through the brush while hunting.

Water Spaniels and Retrievers:There is controversy over the progenitor of the retrieving spaniels. Many suspect that there was an ancient breed of water spaniel, which is now extinct, that was the ancestor for dogs in this group. These dogs typically have long muzzles for carrying game and webbed feet for proficient swimming. Their coat tends to be oily to protect them from cold water.

This group includes: Poodle, Portuguese Water Dog, Labrador Retriever, Golden Retriever, American Water Spaniel.

Pointer:This groups is thought to be one of the most ancient of the sporting breeds. Pointers have excellent sense of smell, and a strong desire to hunt. Their bodies are built for chasing game for many hours. They are strong but not heavily made.

This group includes: Spinone Italiano, Visla, Pointer, Dalmatian, German Short Hair Pointer, German Wirehair Pointer.

Terriers:The first purpose for breeding these dogs was rodent control. They are compact in build, curious and eager to seek out prey. These dogs tend to be very alert, energetic and assertive.

Herding Group:These dogs are built to herd, guard, and move flock. They have a strong sense of order and a good memory for where they have left items. Dogs in this group will herd and/or guard almost anything including children and toys. Herding dogs are divided into those that guard flock, drive sheep and move or sort herds. Herding dogs take direction from humans quite well and are quite easy to train.